Light protection package including monolayer container and monolayer closure

ABSTRACT

A new light protective package which includes a monolayer container and a removable and re-sealable monolayer closure, wherein both the monolayer container and the monolayer closure have an LPF value of at least about 20.

BACKGROUND OF THE INVENTION

Certain compounds and nutrients contained within packages can benegatively impacted by exposure to light. Many different chemical andphysical changes may be made to molecular species as a result of eithera direct, or indirect, exposure to light, which can collectively bedefined as photochemical processes. As described in Atkins,photochemical processes can include primary absorption, physicalprocesses (e.g., fluorescence, collision-induced emission, stimulatedemission, intersystem crossing, phosphorescence, internal conversion,singlet electronic energy transfer, energy pooling, triplet electronicenergy transfer, triplet-triplet absorption), ionization (e.g., Penningionization, dissociative ionization, collisional ionization, associativeionization), or chemical processes (e.g., disassociation or degradation,addition or insertion, abstraction or fragmentation, isomerization,dissociative excitation) (Atkins, P. W.; Table 26.1 PhotochemicalProcesses. Physical Chemistry, 5th Edition; Freeman: New York, 1994;908.). As one example, light can cause excitation of photosensitizerspecies (e.g., riboflavin in dairy food products) that can thensubsequently react with other species present (e.g., oxygen, lipids) toinduce changes, including degradation of valuable products (e.g.,nutrients in food products) and evolution of species that can adjust thequality of the product (e.g., off-odors in food products).

As such, there is a need to provide packaging with sufficient lightprotection properties to allow the protection of the package content(s)and sufficient mechanical properties to withstand shipping, storage, anduse conditions.

The ability of packages to protect substances they contain is highlydependent on the materials used to design and construct the package(reference: Food Packaging and Preservation; edited M. Mathlouthi, ISBN:0-8342-1349-4; Aspen publication; Copyright 1994; Plastic PackagingMaterials for Food; Barrier Function, Mass Transport, Quality Assuranceand Legislation: ISBN 3-527-28868-6; edited by O. G Piringer; A. L.Baner; Wiley-vch Verlag GmBH, 2000, incorporated herein by reference).Preferred packaging materials are designed with consideration for thepenetration of moisture, light, and oxygen often referred to as barriercharacteristics.

Light barrier characteristics of materials used for packaging aredesired to provide light protection to package contents. Methods havebeen described to measure light protection of a packaging material andcharacterize this protection with a “Light Protection Factor” or (LPF)as described in commonly owned U.S. Pat. No. 9,638,679 “Methods forproducing new packaging designs based on photoprotective materials”, thesubject matter which is hereby incorporated by reference in itsentirety.

Titanium dioxide (TiO₂) is frequently used in plastics food packaginglayer(s) at low levels (typical levels of 0.1 weight % to 5 weight %(“weight %” is abbreviated as “wt %” hereinafter) of a composition) toprovide aesthetic qualities to a food package such as whiteness and/oropacity. In addition to these qualities, titanium dioxide is recognizedas a material that may provide light protection of certain entities asdescribed in, for example, U.S. Pat. Nos. 5,750,226; 6,465,062; and US20040195141.

Useful packaging designs are those that provide the required lightprotection and functional performance at a reasonable cost for thetarget application. The cost of a packaging design is in part determinedby the materials of construction and the processing required to createthe packaging design.

Milk packaging is an application where there is a benefit for lightprotection in packages to protect milk from the negative impacts oflight exposure. Light exposure to milk may result in the degradation ofsome chemical species in the milk; this degradation results in adecrease in the nutrient levels and sensory quality of the milk (e.g.,“Riboflavin Photosensitized Singlet Oxygen Oxidation of Vitamin D”, J.M. King and D. B. Min, V 63, No. 1, 1998, Journal of Food Science, page31). Hence protection of milk from light with light protection packagingwill allow the nutrient levels and sensory quality to be preserved attheir initial levels for extended periods of time as compared to milkpackaged in typical packaging that does not have light protection (e.g.,“Effect of Package Light Transmittance on Vitamin Content of Milk. Part2: UHT Whole Milk.” A. Saffert, G. Pieper, J. Jetten; PackagingTechnology and Science, 2008; 21: 47-55).

Additionally, multilayered structures are seen as a means to achievelight protection qualities in package designs. Typically, more than onelayer of material is required for adequate protection of food from lightand mechanical damage. For example, Cook et al. (U.S. Pat. No.6,465,062) present a multilayer packaging container design to achievelight barrier characteristics with other functional barrier layers.Problems associated with multilayered packaging structures are theyrequire more complex processing, additional materials for each layer,higher package cost, and risk delamination of layers. Deficiencies ofmultilayer designs and benefits of monolayer designs are discussed in US20040195141 in section [0022] and [0026]. Moreover, state of the artcaps comprising two or more layers of materials, such as a foil seal orlight block liner, can achieve suitable light protection. However, thesedesigns are deficient as the foil seal or liner layer may be removed ordamaged after the package is opened by the consumer. These additionallayers may be perceived by consumers as only part of the product sealingfunction. Thus, the consumer may remove them, perhaps so the layers orpieces of the layer do not fall into the product. Upon removal of suchadditional layer(s) the cap will not retain the light protection benefitprovided by the layer(s) after the product is opened and the layer(s) isremoved. Thus, such layer(s) may be used for sealing or other functionsbut are not a part of the light protection performance of the capthrough consumer use.

Thus, there is a commercial need to create a monolayer food package thatachieves, or exceeds, the light protection and mechanical strengthproperties of a multilayer package.

The present invention provides solutions to the above-identifieddeficiencies in the art by providing monolayer containers and monolayerclosures that provide sufficient light protection and mechanicalstrength.

SUMMARY OF THE INVENTION

The invention comprises a light protection package that comprises amonolayer container and monolayer closure (e.g., a cap) that considersall portions of the light exposed package design, including all areas ofthe package that allow the potential for light exposure to the productcontained within the package. For example, a light protection packageaccording to the invention can be a light protection dairy container(e.g., a bottle) and removable and re-sealable closure (e.g., a cap).For optimal light protection performance, the container and closure canhave substantially the same light protection performance oralternatively, when the light protection performance of the containerand closure are different, the desired light protection performanceshould be met by the minimum performance level for either the containeror closure.

The invention comprises a light protective package that comprises amonolayer container and a monolayer closure. The monolayer containerand/or monolayer closure can comprise TiO₂ particles. Moreover, themonolayer container and/or monolayer closure can further comprise atleast one color pigment. The TiO₂ particles and at least one colorpigment can be dispersed throughout the container material and/orclosure. The package has superior light protection properties whilemaintaining necessary mechanical properties. The monolayer containerand/or monolayer closure can have a light protection factor (“LPF”)value of 20 or greater, preferably greater than 30, more preferablygreater than 40, more preferably greater than 50, more preferablygreater than 60, more preferably greater than 80, and even morepreferably greater than 100.

In an aspect of the invention the monolayer closure comprises a topportion that is a sufficient thickness produced with light protectionmaterials to provide light protection performance to the closure. In anaspect of the invention the monolayer closure top portion can have athickness of at least about 50 mils.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic drawing of a package according to the invention.

FIG. 2 is a schematic drawing of a package according to the invention.

FIG. 3 is a schematic drawing of a package according to the invention.

FIG. 4 is a schematic drawing of a package according to the invention.

FIG. 5 is a schematic drawing of a removable seal.

FIG. 6 is a graph of data obtained in Example 1.

FIG. 7A is a schematic illustration of the sample holder used todetermine the light protection factor (“LPF”) according to the teachingsof U.S. Pat. No. 9,638,679.

FIG. 7B is a schematic illustration of a modified sample holder used todetermine the LPF of the top portion of plastic caps.

DETAILED DESCRIPTION OF THE DISCLOSURE

The invention comprises a light protection package that comprises amonolayer container and monolayer closure (e.g., a cap) that considersall portions of the light exposed package design, including all areas ofthe package that allow the potential for light exposure to the productcontained within the package. For example, a light protection packageaccording to the invention can be a light protection dairy container(e.g., a bottle) and removable and re-sealable closure (e.g., a cap).For optimal light protection performance, the container and closure canhave substantially the same light protection performance oralternatively, when the light protection performance of the containerand closure are different, the desired light protection performanceshould be met by the minimum performance level for either the containeror closure.

In this disclosure “comprising” is to be interpreted as specifying thepresence of the stated features, integers, steps, or components asreferred to, but does not preclude the presence or addition of one ormore features, integers, steps, or components, or groups thereof.Additionally, the term “comprising” is intended to include examplesencompassed by the terms “consisting essentially of” and “consistingof.” Similarly, the term “consisting essentially of” is intended toinclude examples encompassed by the term “consisting of.”

In this disclosure, when an amount, concentration, or other value orparameter is given as either a range, typical range, or a list of uppertypical values and lower typical values, this is to be understood asspecifically disclosing all ranges formed from any pair of any upperrange limit or typical value and any lower range limit or typical value,regardless of whether ranges are separately disclosed. Where a range ofnumerical values is recited herein, unless otherwise stated, the rangeis intended to include the endpoints thereof, and all integers andfractions within the range. It is not intended that the scope of thedisclosure be limited to the specific values recited when defining arange.

In this disclosure, terms in the singular and the singular forms “a,”“an,” and “the,” for example, includes plural references unless thecontent clearly dictates otherwise. Thus, for example, reference to“TiO₂ particle”, “a TiO₂ particle”, or “the TiO₂ particle” also includesa plurality of TiO₂ particles. All references cited in this patentapplication are herein incorporated by reference.

Monolayer is defined as a structural component of the package (e.g., thecontainer and the closure (the closure may include threaded portion toassist in re-sealing the closure and container)) that is comprised of asingle layer of material. The material in its cross section does nothave differential layers with different compositions or functionalproperties. The monolayer is structural as it contains the contents ofthe package, however the package may be rigid (e.g., like a plasticbottle) or flexible (e.g., like a plastic pouch) or a combination ofrigid and flexible portions.

Layers may be applied to the package components that are not structural.For example, decorative sleeves, stickers, wraps or print may be appliedto cover portions of the package to provide branding, consumerinformation, and adjust the package texture and appearance. These layersare considered non-structural layers and thus a package comprising oneor more components that are not structural is still considered monolayerin its structural design according to the invention.

A co-extruded package structure is not considered a monolayer packagedesign according to the invention.

The removable and re-sealable closure (such as a bottle cap, which maycomprise threads) may contain an optional insert which, if it can bereadily removed, is also considered a layer that is nonstructural. Forexample, a cap may contain a layer to facilitate sealing of the packagewhen the cap threads are engaged with a corresponding threaded portionof the container. Moreover, a cap or container may include a seal (e.g.,foil or plastic) that is removed and discarded for normal consumer useof the package.

If a package container or closure contains a seal that is removedirreversibly for removal of the product from the package, then thecontainer or closure is still considered to be a monolayer design. Thisseal that is removed is insufficient as a light protection layer as itis only available for light protection until the seal is removed. Forexample, a seal layer such as a plastic seal or a foil seal would beconsidered irreversibly removed layers.

If the seal is integrated into the cap it is not a monolayer capaccording to the invention. Further if the cap contains anotherfunctional layer, such as an integrated oxygen scavenger layer oradditional gasket-like material to improve the seal, it is not amonolayer cap. Aesthetic layers on the cap such as printed ink orstickers or partial coverage such as tamper evident rings can be usedwith a monolayer cap as the primary cap is still a single complete layerof material.

The invention comprises a light protective package that comprises amonolayer container and a removable and re-sealable monolayer closure(e.g., a cap). The monolayer container and/or monolayer closure cancomprise TiO₂ particles. Moreover, the monolayer container and/ormonolayer closure can further comprise at least one color pigment. TheTiO₂ particles and at least one color pigment can be dispersedthroughout the container material and/or closure. The package hassuperior light protection properties while maintaining necessarymechanical properties. The monolayer container and/or closure can have alight protection factor (“LPF”) value of 20 or greater, preferablygreater than 30, more preferably greater than 40, more preferablygreater than 50, more preferably greater than 60, more preferablygreater than 80, and even more preferably greater than 100. A detaileddescription of LPF and measuring LPF values is described in commonlyowned U.S. Pat. No. 9,638,679 “Methods for producing new packagingdesigns based on photoprotective materials” and U.S. Pat. No. 9,372,145“Devices for determining photoprotective materials” the subject matterof both patents is incorporated herein by reference. Additionalinformation may be found in the example sections of these patents. LPFvalues used herein are determined according to the teachings in thesetwo patents.

The invention also comprises a monolayer closure comprising a topportion and side wall(s) portion. The closure top portion is asufficient thickness produced with light protection materials to providelight protection performance to the closure. The closure top portion canhave an LPF value of 20 or greater, preferably greater than 30, morepreferably greater than 40, more preferably greater than 50, morepreferably greater than 60, more preferably greater than 80, and evenmore preferably greater than 100. The monolayer closure additionallycomprises light protection TiO₂ materials. The monolayer closureprovides suitable light protection performance in the closure topportion while overcoming injection molding closure production processchallenges presented with the use of light protection materials athigher levels. This allows the processing performance of the injectionmolding equipment used to produce the closures to be maintained and themechanical features (e.g., the threads on a screw top closure) of theseclosures to be produced with their desired functionality (e.g., sealingperformance).

The monolayer closure can be used in conjunction with any container(e.g., a bottle). However, in an aspect of the invention the monolayerclosure can be used in conjunction with a light protection containeraccording to the present invention. Where the closure threads or sidewall(s) engage or seal with the container, the primary container canprovide light protection performance; however, as a monolayer, the topportion of the closure does not have any additional package layer toprovide light protection and thus it must provide the light protectionperformance. Suitable light protection performance is achieved with themonolayer closure of the invention which comprises a thicker closure topportion (relative to the thickness of the cap side wall(s)) whereinlight protection TiO₂ materials are provided throughout the closure. Inan aspect of the invention the closure comprises a top portion having athickness of at least about 50 mil.

Although the closure of the present invention can be used with anysuitable container, preferred containers include the containers of thepresent invention and additionally include the containers disclosed incommonly owned US20160083554, WO2016/196529, and PCT patent applicationPCT/US2017/066105, the subject matter of each is hereby incorporated byreference in their entirety.

Referring to the Figures, aspects of the invention will be described.FIGS. 1-4 demonstrate various possible packages 1 according to theinvention, where the packages 1 comprise monolayer container (e.g., abottle) 2 and monolayer closure (e.g., a cap) 3. As shown, closures 3are removable and re-sealable. FIGS. 2 and 4 further show additional,non-structural layers 5, such as product labels that may includeconsumer information, brand name, etc. The monolayer container can alsobe provided with a removable seal 4 over an opening in the monolayercontainer. FIG. 5 demonstrates such an embodiment that includes amonolayer container 2 with removable seal 4. The removable seal 4 can beconstructed of any suitable material, such as plastic or foil, and mayor may not be provided with a pull-tab as shown.

The titanium dioxide (and optionally at least one color pigment) can bedispersed and processed in package production processes by incorporatinga masterbatch, and preferably processed into a package using blowmolding methods and/or injection molding. The masterbatch can be solidpellets. The TiO₂ (and optional color pigment) could also be deliveredin other forms, such as in a liquid delivery form and do not have to bedelivered in one single masterbatch formulation.

In an aspect of the invention the TiO₂ particles can be coated with ametal oxide, preferable alumina, and then an additional organic layer.The treated TiO₂ is an inorganic particulate material that can beuniformly dispersed throughout a polymer melt, and imparts color andopacity to the polymer melt. Reference herein to TiO₂ without specifyingadditional treatments or surface layers does not imply that it cannothave such layers.

It is preferred that the metal oxide is selected from the groupconsisting of silica, alumina, zirconia, or combinations thereof. It ismost preferred that the metal oxide is alumina. It is preferred that theorganic coating material on the TiO₂ is selected from the groupconsisting of an organo-silane, an organo-siloxane, a fluoro-silane, anorgano-phosphonate, an organo-acid phosphate, an organo-pyrophosphate,an organo-polyphosphate, an organo-metaphosphate, an organo-phosphinate,an organo-sulfonic compound, a hydrocarbon-based carboxylic acid, anassociated ester of a hydrocarbon-based carboxylic acid, a derivative ofa hydrocarbon-based carboxylic acid, a hydrocarbon-based amide, a lowmolecular weight hydrocarbon wax, a low molecular weight polyolefin, aco-polymer of a low molecular weight polyolefin, a hydrocarbon-basedpolyol, a derivative of a hydrocarbon-based polyol, an alkanolamine, aderivative of an alkanolamine, an organic dispersing agent, or a mixturethereof. It is more preferred that the organic material is anorgano-silane having the formula: R⁵ _(x)SiR⁶ _(4−x) wherein R⁵ is anonhydrolyzable alkyl, cycloalkyl, aryl, or aralkyl group having atleast 1 to about 20 carbon atoms; R⁶ is a hydrolyzable alkoxy, halogen,acetoxy, or hydroxy group; and x=1 to 3. It is most preferred that theorganic material is Octyltriethoxysilane. In a further aspect of theinvention the metal oxide is alumina and the organic material isoctyltriethoxysilane.

In an aspect of the invention the monolayer container and/or monolayerclosure can have a concentration of TiO₂ particles of from above 0 wt %to about 8 wt % of the monolayer, preferably 0.5 to 8 wt % of themonolayer, more preferably 0.5 to 4 wt % of the monolayer. In anotheraspect of the invention, the monolayer container and the monolayerclosure can be comprised of different materials or different levels ofthe same or different materials. The melt processable resin(s) can beselected from the group of polyolefins. In an aspect of the inventionthe melt processable resin is preferably a high-density polyethylene andthe monolayer container has a thickness of 8 mil to 50 mil, or morepreferably 10 mil to 35 mil.

TiO₂ particles may be in the rutile or anatase crystalline form. It iscommonly made by either a chloride process or a sulfate process. In thechloride process, TiCl₄ is oxidized to TiO₂ particles. In the sulfateprocess, sulfuric acid and ore containing titanium are dissolved, andthe resulting solution goes through a series of precipitation steps toyield TiO₂. Both the sulfate and chloride processes are described ingreater detail in “The Pigment Handbook”, Vol. 1, 2nd Ed., John Wiley &Sons, NY (1988), the teachings of which are incorporated herein byreference.

TiO₂ particles may have a medium diameter range of about 100 nm to about250 nm as measured by X-Ray centrifuge technique, specifically utilizinga Brookhaven Industries model TF-3005W X-ray Centrifuge Particle SizeAnalyzer. The crystal phase of the TiO₂ is preferably rutile. The TiO₂after receiving surface treatments can have a mean size distribution indiameter of about 100 nm to about 400 nm, more preferably about 100 nmto about 250 nm. Nanoparticles (those have mean size distribution lessthan about 100 nm in their diameter) could also be used in thisinvention but may provide different light protection performanceproperties.

The TiO₂ particles may be substantially pure, such as containing onlytitanium dioxide, or may be treated with other metal oxides, such assilica, alumina, and/or zirconia. TiO₂ particles coated/treated withalumina are preferred in the present invention. The TiO₂ particles maybe treated with metal oxides, for example, by co-oxidizing orco-precipitating inorganic compounds with metal compounds. If a TiO₂particle is co-oxidized or co-precipitated, then up to about 20 wt % ofthe other metal oxide, more typically, 0.5 to 5 wt %, most typicallyabout 0.5 to about 1.5 wt % may be present, based on the total particleweight.

The treated titanium dioxide can be formed, for example, by the processcomprising: (a) providing titanium dioxide particles having on thesurface of said particles a substantially encapsulating layer comprisinga pyrogenically-deposited metal oxide or precipitated inorganic oxides;(b) treating the particles with at least one organic surface treatmentmaterial selected from an organo-silane, an organo-siloxane, afluoro-silane, an organo-phosphonate, an organo-acid phosphate, anorgano-pyrophosphate, an organo-polyphosphate, an organo-metaphosphate,an organo-phosphinate, an organo-sulfonic compound, a hydrocarbon-basedcarboxylic acid, an associated ester of a hydrocarbon-based carboxylicacid, a derivative of a hydrocarbon-based carboxylic acid, ahydrocarbon-based amide, a low molecular weight hydrocarbon wax, a lowmolecular weight polyolefin, a co-polymer of a low molecular weightpolyolefin, a hydrocarbon-based polyol, a derivative of ahydrocarbon-based polyol, an alkanolamine, a derivative of analkanolamine, an organic dispersing agent, or a mixture thereof; and (c)optionally, repeating step (b).

An example of a method of treating or coating TiO₂ particles withamorphous alumina is taught in Example 1 of U.S. Pat. No. 4,460,655incorporated herein by reference. In this process, fluoride ion,typically present at levels that range from about 0.05 wt % to 2 wt %(total particle basis), is used to disrupt the crystallinity of thealumina, typically present at levels that range from about 1 wt % toabout 8 wt % (total particle basis), as the latter is being depositedonto the titanium dioxide particles. Note that other ions that possessan affinity for alumina such as, for example, citrate, phosphate orsulfate can be substituted in comparable amounts, either individually orin combination, for the fluoride ion in this process. The performanceproperties of white pigments comprising TiO₂ particles coated withalumina or alumina-silica having fluoride compound or fluoride ionsassociated with them are enhanced when the coated TiO₂ is treated withan organosilicon compound. The resulting compositions are particularlyuseful in plastics applications. Further methods of treating or coatingparticles of the present invention are disclosed, for example, in U.S.Pat. No. 5,562,990 and US 2005/0239921, the subject matter of which isherein incorporated by reference.

Titanium dioxide particles may be treated with an organic compound suchas low molecular weight polyols, organosiloxanes, organosilanes,alkylcarboxylic acids, alkylsulfonates, organophosphates,organophosphonates and mixtures thereof. The preferred organic compoundis selected from the group consisting of low molecular weight polyols,organosiloxanes, organosilanes and organophosphonates and mixturesthereof and the organic compound is present at a loading of between 0.2wt % and 2 wt %, 0.3 wt % and 1 wt %, or 0.7 wt % and 1.3 wt % on atotal particle basis. The organic compound can be in the range of about0.1 to about 25 wt %, or 0.1 to about 10 wt %, or about 0.3 to about 5wt %, or about 0.7 to about 2 wt %. One of the preferred organiccompounds used in the present invention is polydimethyl siloxane; otherpreferred organic compounds used in the present invention includecarboxylic acid containing material, a polyalcohol, an amide, an amine,a silicon compound, another metal oxide, or combinations of two or morethereof.

In a preferred embodiment, the at least one organic surface treatmentmaterial is an organo-silane having the formula: R⁵ _(x)SiR⁶ _(4−x)wherein R⁵ is a nonhydrolyzable alkyl, cycloalkyl, aryl, or aralkylgroup having at least 1 to about 20 carbon atoms; R⁶ is a hydrolyzablealkoxy, halogen, acetoxy, or hydroxy group; and x=1 to 3.Octyltriethoxysilane is a preferred organo-silane.

The following TiO₂ pigments may be useful TiO₂ particles in the presentinvention: Chemours Ti-Pure™ R-101, R-104, R-105, R-108, R-350, TS-1600,and TS-1601. Other TiO₂ grades with similar size and surface treatmentsmay also be useful in the invention.

When the TiO₂ particles and color pigments are used in a polymercomposition/melt, the melt-processable polymer that can be employedtogether with the TiO₂ particles and color pigments comprise a highmolecular weight polymer, preferably thermoplastic resin. By “highmolecular weight” it is meant to describe polymers having a melt indexvalue of 0.01 to 50, typically from 2 to 10 as measured by ASTM methodD1238-98. By “melt-processable,” it is meant a polymer must be melted(or be in a molten state) before it can be extruded or otherwiseconverted into shaped articles, including films and objects having fromone to three dimensions. Also, it is meant that a polymer can berepeatedly manipulated in a processing step that involves obtaining thepolymer in the molten state.

Polymers that are suitable for use in this invention include, by way ofexample but not limited thereto, polymers of ethylenically unsaturatedmonomers including olefins such as polyethylene, polypropylene,polybutylene, and copolymers of ethylene with higher olefins such asalpha olefins containing 4 to 10 carbon atoms or vinyl acetate; vinylssuch as polyvinyl chloride, polyvinyl esters such as polyvinyl acetate,polystyrene, acrylic homopolymers and copolymers; phenolics; alkyds;amino resins; polyamides; phenoxy resins, polysulfones; polycarbonates;polyesters and chlorinated polyesters; polyethers; acetal resins;polyimides; and polyoxyethylenes. Mixtures of polymers are alsocontemplated. Polymers suitable for use in the present invention alsoinclude various rubbers and/or elastomers, either natural or syntheticpolymers based on copolymerization, grafting, or physical blending ofvarious diene monomers with the above-mentioned polymers, all asgenerally known in the art. Typically, the polymer may be selected fromthe group consisting of polyolefin, polyvinyl chloride, polyamide andpolyester, and mixture of these. More typically used polymers arepolyolefins. Most typically used polymers are polyolefins selected fromthe group consisting of polyethylene, polypropylene, and mixturethereof. A typical polyethylene polymer is low density polyethylene(LDPE), linear low density polyethylene (LLDPE), and high densitypolyethylene (HDPE). Additional polymers include, for example,polyethylene Terephthalate (PET, PETE), polypropylene (PP), polystyrene(PS), and polyvinyl chloride (PVC, vinyl).

A wide variety of additives may be present in the package of thisinvention as necessary, desirable, or conventional. Such additivesinclude polymer processing aids such as fluoropolymers,fluoroelastomers, etc., catalysts, initiators, antioxidants (e.g.,hindered phenol such as butylated hydroxytoluene), blowing agent,ultraviolet light stabilizers (e.g., hindered amine light stabilizers or“HALS”), organic pigments including tinctorial pigments, plasticizers,antiblocking agents (e.g. clay, talc, calcium carbonate, silica,silicone oil, and the like) leveling agents, flame retardants,anti-cratering additives, and the like. Additional additives furtherinclude plasticizers, optical brighteners, adhesion promoters,stabilizers (e.g., hydrolytic stabilizers, radiation stabilizers,thermal stabilizers, and ultraviolet (UV) light stabilizers),antioxidants, ultraviolet ray absorbers, anti-static agents, colorants,dyes or pigments, delustrants, fillers, fire-retardants, lubricants,reinforcing agents (e.g., glass fiber and flakes), processing aids,anti-slip agents, slip agents (e.g., talc, anti-block agents), and otheradditives.

Any melt compounding techniques known to those skilled in the art may beused to process the compositions of the present invention. Packages ofthe present invention may be made after the formation of a masterbatch.The term masterbatch is used herein to describe a mixture of TiO₂particles and color pigments (collectively called solids) which can bemelt processed at high solids to resin loadings (generally 50-80 wt % byweight of the total masterbatch) in high shear compounding machinerysuch as Banbury mixers, continuous mixers or twin screw mixers, whichare capable of providing enough shear to fully incorporate and dispersethe solids into the melt processable resin. The resultant meltprocessable resin product is commonly known as a masterbatch, and istypically subsequently diluted or “letdown” by incorporation ofadditional virgin melt processable resin in plastic productionprocesses. The letdown procedure is accomplished in the desiredprocessing machinery utilized to make the final consumer article,whether it is sheet, film, bottle, package or another shape. The amountof virgin resin utilized and the final solids content is determined bythe use specifications of the final consumer article. The masterbatchcomposition of this invention is useful in the production of shapedarticles.

In another embodiment of the present invention, the titanium dioxide andcolor pigment are supplied for processing into the package as amasterbatch concentrate. Preferred masterbatch concentrates typicallyhave titanium dioxide content of greater than 40 wt %, greater than 50wt %, greater than 60 wt %, greater than 70 wt %, or greater than 80 wt%. Preferred color concentrate masterbatches are solid. Liquid colorconcentrates and/or a combination of liquid and solid color concentratescould be used.

In an aspect of the invention, the amount of titanium dioxide particlesin the package of the invention can be any suitable amount which resultsin the desired LPF value. For example, the amount of titanium dioxideparticles contained in the container and/or closure can be at leastabout 0.5 wt %, and preferably at least about 0.1 wt %. In an aspect ofthe invention the titanium dioxide particles in the container and/orclosure can be from about 0.5 wt % to about 20 wt %, and is preferablyfrom about 0.1 wt % to about 15 wt %, more preferably 5 wt % to 10 wt %.In a further aspect of the invention the titanium dioxide particles inthe container and/or closure can be from at least about 0.5 wt %, 0.6 wt%, 0.7 wt %, 0.8 wt %, 0.9 wt %, 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %,6 wt %, 7 wt %, 8 wt %, 9 wt %, 10 wt %, 11 wt % to 12 wt %. In anaspect of the invention the titanium dioxide particles in the containerand/or closure can be any amount between 0.1 wt % and 12 wt % (all wt %are based on the total weight of the monolayer of the container and/orclosure).

A package is typically produced by melt blending the masterbatchcontaining the titanium dioxide and color pigment with a second highmolecular weight melt-processable polymer to produce the desiredcomposition used to form the finished monolayer package. The masterbatchcomposition and second high molecular weight polymer can be meltblended, using any means known in the art, as disclosed above in desiredratios to produce the desired composition of the final monolayerpackage. In this process, twin-screw extruders are commonly used. Theresultant melt blended polymer is extruded or otherwise processed toform a package, sheet, or other shaped article of the desiredcomposition. The melt blended polymer may be injection into a preformfor subsequent stretch blow molding processing.

The package may have one or more additional functional layer or layers.Such layer or layers may be formed from a label, paper, printed ink,wrap, coating treatment or other material. The layer or layers may coverpart or all of the surface of the package. The functional layer orlayers may be on the internal walls of the package. The functional layeror layers may contribute some light protection performance to thepackage, but the primary light protection monolayer providessubstantially more light protection than the light protection providedby the functional layer or layers.

Layers applied for aesthetic purposes, including for branding andproduct information like nutrition and ingredient labels, may not becomplete layers. For example, labels may only cover a small area on thesurface area of a package or a wrap may cover the sides of a package,but not the base. Such incomplete layers cannot provide fully effectivelight protection as light can enter the package through the surfaces ofthe package that are not covered by the layer. As light can enter thepackage from any direction, having complete coverage of the package isan important consideration in the package light protection design.Hence, aesthetic layers are often deficient in providing the primarymode of light protection for a package design. Functional layerstypically have a narrowly defined purpose, such as providing gas barrierproperties or to prevent interactions of layers or to bind two layerstogether and thus are not designed for light protection. The presentinvention addresses this challenge by providing and designing lightprotection directly into the primary package thus imparting lightprotection to substantially all of the package surface.

The monolayer container is provided with a removable and re-sealablemonolayer closure (e.g., cap). In an aspect of the invention themonolayer closure can comprise substantially the same material as themonolayer container. In a further aspect of the invention the monolayerclosure can be a different material from the monolayer container and canalso be a different color than the monolayer container or the samecolor.

In an aspect of the invention, extrusion blow molding can be used toproduce the monolayer container and/or monolayer cap. In yet anotherembodiment, a pre-form can be produced by injection molding used toproduce the monolayer container and/or monolayer cap using a stretchblow molding process.

General Steps of Blow Molding

Blow molding is a molding process in which air pressure is used toinflate soft plastic into a mold cavity. Blow molding techniques havebeen disclosed in the art, for example in “Petrothene® Polyolefins . . .a processing guide”, 5th Edition, 1986, U.S.I Chemicals. Blow molding isan important industrial process for making one-piece hollow plasticparts with thin walls, such as bottles and similar containers. Blowmolding is accomplished in two stages: (1) fabrication of a startingtube of molten plastic, called a parison, or an injection molded preformthat is properly heated to a molten state; and (2) inflation of the tubeor preform in a mold to the desired final shape. Forming the parison orpreform is accomplished by either of two processes: extrusion orinjection molding.

Extrusion blow molding contains four steps: (1) extrusion of parison;(2) parison is pinched at the top and sealed at the bottom around ametal blow pin as the two halves of the mold come together; (3) the tubeis inflated so that it takes the shape of the mold cavity; and (4) moldis opened to remove the solidified part.

Injection blow molding contains the same steps as blow molding; however,is the injection molded preform is used rather than an extruded parison:(1) preform is injection molded; (2) injection mold is opened andpreform is transferred to a blow mold; (3) preform is heated to becomemolten and inflated to conform to a blow mold; and (4) blow mold isopened and blown product is removed.

Blow molding is limited to thermoplastics. Polyethylene is the polymermost commonly used for blow molding; in particular, high density andhigh molecular weight polyethylene (HDPE and HMWPE). In comparing theirproperties with those of low density PE given the requirement forstiffness in the final product, it is more economical to use these moreexpensive materials because the container walls can be made thinner.Other blow moldings are made of polypropylene (PP), polyvinylchloride(PVC), and polyethylene terephthalate (PET).

The package finds utility to contain dairy and non-dairy milk products,usually liquids. Liquid should be understood to mean a liquid that istaken or derived from a protein source, such as coconut, soybean, cows,goats, etc. Non-dairy milk includes, for example, liquid derived fromalmonds, cashews, coconuts, flax, soy, rice, hazelnut, hemp, quino, etc.

Measuring Light Protection Performance or LPF

The LPF value quantifies the protection a packaging material can providefor a light sensitive entity in a product when the packaged product isexposed to light. The LPF value for a packaging material is quantifiedin our experiment as the time when half of the product light sensitiveentity concentration has been degraded or otherwise undergonetransformation in the controlled experimental light exposure conditions.Hence, a product comprising one or more light sensitive entitiesprotected by a high LPF value package can be exposed to a larger dose oflight before changes will occur to the light sensitive entity versus theproduct protected by a low LPF value package.

A detailed description of measuring LPF value is further described incommonly owned U.S. Pat. No. 9,638,679 titled, “Methods for DeterminingPhoto Protective Materials” and U.S. Pat. No. 9,372,145 titled, “Devicesfor Determining Photo Protective Materials incorporated herein byreference. Additional information may be found in the Examples herein.The LPF values reported in the Examples that follow were measuredaccording to the teachings of the above patent applications.

The current invention is focused on identifying new packages with lightprotective properties that protect species from photo chemical process(e.g., photo oxidation). Photochemical processes alter entities such asriboflavin, curcurim, myoglobin, chlorophyll (all forms), vitamin A, anderythrosine under the right conditions. Other photosensitive entitiesthat may be used in the present invention include those found in foods,cosmetics, pharmaceuticals, biological materials such as proteins,enzymes, and chemical materials. In the present invention, LPFprotection is reported for the light sensitive entity riboflavin.Riboflavin is the preferred entity to track performance for dairyapplications although other light sensitive entities may also beprotected from the effects of light.

EXAMPLES Treated TiO₂

Treated TiO₂ particles comprising an inorganic surface modificationusing alumina hydrous oxide, fluoride ions and organosilicon compoundwere prepared substantially according to the teachings of U.S. Pat. No.5,562,990.

Production of Plaque Samples for LPF Evaluation

Low density polyethylene (LDPE) (DuPont 20, DuPont, Wilmington, Del.)and TiO₂ and color pigment masterbatch concentrate pellets werepre-weighed in amounts to yield the final ratios desired in batches of190 g. Concentrate and resin mixtures were compounded on a two-roll mill(Stewart Bolling & Co., Cleveland, Ohio) at 220-240° F. with a gap of0.035 in. The initial melt was performed with rollers stationary, androller speed was slowly increased from 10 ft/min to final speeds of 45and 35 ft/min for front and back rollers, respectively. Material was cutoff the rollers, folded, and re-applied a total of 10 times to ensurecomplete mixing. The material was removed from the rollers for the finaltime as a single sheet and this stock was immediately cut into smallerpieces to better fit the compression mold. Compression molding of rigidplaques from this material was performed using two hydraulic presses(Carver, Wabash, Ind.) in sequence, the first heated to 350° F. to meltand mold the material and the second water-cooled to freeze the plaqueshape. Compounded LDPE material was placed between Mylar sheets over amold between platens, held for 2 min at a pressure of 25 tons in the hotpress, and then for 2 min at 12.5 tons in the cold press. The Mylar wasremoved and excess plastic around each plaque was trimmed, yieldingrectangular plaques about 5 cm by 10 cm with average thickness ofapproximately 30 mil. This procedure was repeated at different levels ofmasterbatch concentrates to produce the desired series of samples withvaried composition.

Example 1

As disclosed in commonly owned WO2016/196529, the light protectionperformance of a packaging material can be quantified with a lightprotection factor (“LPF”) value. Further, as disclosed in commonly ownedU.S. Pat. No. 9,638,679, sample holders can be selected to holddifferent types of packaging samples.

The cap LPF measurements employed a specialized cap holder to studythese smaller packaging parts, as shown in FIG. 7B. As this specializedcap holder yields a smaller light exposed area, the resultant LPFnumbers are not directly comparable to LPF numbers using the standardholder, as shown in FIG. 7A, presented in the examples of U.S. Pat. No.9,638,679. These LPF numbers using the cap holder are denoted LPFc.

To renormalize the LPFc numbers to the same scale as the standard squareLPF evaluation sample holder used for the remaining evaluations of thebottle and wrap samples, a series of packages were evaluated in bothsample holders to build a correlation between the LPF and LPFc data.This correlation was used to renormalize the measured LPFc numbers tothe standard LPF scale. The resultant data from these experiments iscaptured in Table 1 and represents the average of at least two replicateevaluations.

TABLE 1 Sample ID LPF LPFc Blank (no sample) 0.18 0.29 Opacity 3 Film(2% R-104) 1.69 2.83 MA-1-01-V-62 smooth 7.40 10.50 MA-1-04-V-62 smooth30.11 40.03

A linear regression was performed on the data in Table 1 to a simpley=m×model with LPFc as y, LPF as x, and m as the fitted slope. Anexcellent correlation was observed with a correlation coefficient (R²)value of 0.9993 and a slope of 1.3355 is shown in FIG. 6.

Example 2

A series of liquid dairy food products in plastic packages werepurchased from retail food stores. These food products selected aspackages of interest as they were in packages with light protectionfeatures. These packages consisted of monolayer plastic bottles withadditional layers in some samples including labels or wraps coveringportions of the bottle surface, with plastic closures or caps. In thisseries of products, there were no additional layers under the cap (e.g.,foils or seals). The packages are described below.

-   -   Package 140: Dairy Pure Milk (distributed by Dean Foods) ½        gallon HDPE package that is white in appearance with green LDPE        cap.    -   Package 141: Fairlife (distributed by Coca Cola), ½ gallon PET        package that is white in appearance with printed wrap and white        HDPE cap.    -   Package 142: Boost (distributed by Nestle), 8 oz. PET package        that is natural resin in appearance with printed wrap and red        cap with a white insert under the cap top portion.

Applying the teachings of WO2016/196529, U.S. Pat. No. 9,372,145, andU.S. Pat. No. 9,63,679 and Example 1, this series of package samples wasevaluated for their LPF values, or light protection performances, bymeasuring the performances of the individual package componentsincluding the bottle, the bottle plus wrap composite (where applicable),and cap. The bottle and bottle with wrap composite were measured for LPFas taught in the examples of U.S. Pat. No. 9,63,679. The caps wereevaluated using the methods of the examples of U.S. Pat. No. 9,63,679but also the cap holder described in Example 1 to yield the LPFc valuesand the data was normalized using the equation of Example 1 and reportedon an LPF basis. All LPF data is reported in Table 2.

TABLE 2 LPF Sample ID Bottle Bottle with wrap Cap 140 11.9 NA 3.1 141150.4 >>100 9.1 142 <1 >100 >100

For a light protection package design of the claimed invention, an LPFof greater than 20 is needed for all the package components. As can beseen in the data table, the LPF value of packages varies substantiallyacross the components.

Package 140 has components that are all less than LPF 12 and thus wouldnot be suitable for the application.

Package 141 has a wrap that is LPF of greater than 100 and a bottle thatis LPF150, but the LPF of the cap is only LPF 12 and thus the design isnot of sufficient light protection performance due to the deficienciesof the cap.

Package 142 has a bottle with low light protection of LPF less than 1.The wrap offers improved performance but is not complete and leavesbottle areas exposed to light. The cap provides a high light protectionperformance with an LPF of greater than 100; however, this cap is not amonolayer as it has an insert under the top portion.

Through these examples we do not find a monolayer design of a bottleplus cap that is able to provide sufficient light protection of LPF 20or greater. Further we did not find suitable design elements that couldbe combined across these packages to provide the solution claimed in theinvention of the application.

Example 3

A plastic package including a bottle and closure of the claimedinvention were designed to contain liquid dairy product. The plasticpackage components including a bottle and cap were produced andevaluated using the methods of Example 1 and 2. This package consistedof a monolayer plastic bottle comprising polyethylene terephthalate(PETE or PET) with Ti-Pure™ TS-1601 Treated Titanium Dioxide and amonolayer plastic cap comprising high density polyethylene (HDPE) withTi-Pure™ TS-1600 Treated Titanium Dioxide.

These packaging components were produced using standard packageproduction processes known to those that are skilled in the art. Thebottle was produced by injection stretch blow molding and the Ti-Pure™titanium dioxide was added to the injection molding process as amasterbatch along with natural resin to produce the preform. The preformwas then used to produce the bottle by stretch blow molding. The cap wasproduced by injection molding and the Ti-Pure™ titanium dioxide wasadded to the injection molding process as a masterbatch and added withnatural resin.

The stretch blow molding process yielded a bottle with a wall thicknessof 24.5 mil and a TS-1601 composition of 7.0 wt %. The cap was producedto a top portion thickness of 31.8 mil and a TS-1600 composition of 3.8wt %. There were no additional layers under the cap (e.g., foils orseals). The bottle and cap were evaluated for their LPF performances.The LPF performance of the bottle was greater than LPF 100. The LPFperformance on the cap was LPF 46.

The performance objective was to create a package with LPF above 40 andas both the bottle and cap tested higher for LPF than this threshold,the design criteria were achieved.

Comparative Example 1

This example demonstrates the ability to measure and quantify thedeficiency of current white caps on certain, representative retail dairybeverage packages.

Using the LPF measurement method disclosed in commonly owned U.S. Pat.No. 9,638,679, a modified sample holder (FIG. 7B) is applied versus thatpresented in the examples of U.S. Pat. No. 9,638,679 (FIG. 7A). Thismodified holder allowed for the assessment of the small plastic bottlecaps.

FIG. 7A is a schematic illustration of the sample holder disclosed inU.S. Pat. No. 9,638,679, while FIG. 7B is a schematic illustration of amodified sample holder for a cap used to isolate the light exposure tothe cap top portion of the cap and then to direct this light to the topportion in a controlled fashion. The modified, specialized holder isuseful for study of bottle caps and closures which play an importantrole in the light protection performance of a package. A lightprotection performance measurement taken with this modified cap sampleholder is denoted LPFc.

Using the cap sample holder, white caps obtained from dairy beveragepackages purchased at retail were measured for cap top portion lightprotection performance, LPFc. In addition, the caps were characterizedfor thickness in their top portion where each reported value representsan average of several measurements taken over the cap top portion inareas without features (e.g., raised symbols or codes impressed into thecap). The results are provided in Table 4, below.

TABLE 4 Part Description Thickness (mil) LPF_(c) White cap from FairlifePower Shot 45.2 12.7 White cap from Mueller 29.5 11.4 FruchtbuttermilchWhite cap from Oberweis Milk 29.3 3.7

The measured light protection factor of the caps is all below LPFc15,indicating a low light protection performance. Light protectionperformances of LPFc50 or higher are desired for this application toensure preservation of the nutrient content in the packaged product. Thetop portion thicknesses of the caps are all below 46 mil. All of thecaps evaluated were below the LPFc50 target indicating that lightprotection is insufficient and that light can enter the package throughthe cap top portion and cause detrimental effects to the nutrients andsensory quality (e.g., color, odor, flavor) of the packaged product.

Example 5

This example illustrates how increasing the top portion thickness canresult in increasing the cap LPFc and achieve the desire lightprotection performance in this part of a package design.

LPFc was measured as described in Comparative Example 1 on a set ofwhite parts prepared to simulate a cap top portion. This set of samplesdemonstrates the impact on light protection performance of increasingtop portion thickness on a cap. The white parts were produced byinjection molding, the same processing typically used for capproduction. The parts were composed of polyethylene and surface treatedTi-Pure™ TiO₂ (TS-1600, available from the Chemours Company, Wilmington,Del.) at a loading of 1 wt % added to the cap using a 50 wt % Ti-Pure™TS-1600 TiO₂ masterbatch. It is noted that this level of TiO₂ can beutilized in injection molding processes by one skilled in the artwithout difficulty. For this design an LPFc of greater than 100 wasdesired. The results of the measurements are provided in Table 5.

TABLE 5 Part Description Thickness (mil) LPF_(c) White step 1 34.7 24.9White step 2 55.8 40.3 White step 3 105.1 107.0

These data demonstrate that for a fixed composition of Ti-Pure™ TiO₂ inpolyethylene, by increasing the thickness of the material by about 3times, the light protection performance is increased about 4.3 times.Thus, for a cap prepared with this same composition, increased lightprotection can be obtained with a thicker top cap portion.

For the design objective of achieving a LPFc of greater than 50, thethickness of the white step 3 sample provides the desired lightprotection performance. Further, the data in Table 5 can be modeled withan exponential function and with the model it is predicted that LPFc of50 can be achieved with a thickness of 67.6 mil with this samecomposition.

What is claimed is:
 1. A package comprising a monolayer container and aremovable and re-sealable monolayer closure, wherein both the monolayercontainer and the monolayer closure have an LPF value of at least about20.
 2. The package of claim 1, wherein the monolayer container and themonolayer closure have the same LPF value.
 3. The package of claim 1,wherein the package further comprises a removable seal covering anopening in the monolayer container.
 4. The package of claim 1, whereinthe LPF is at least about
 30. 5. The package of claim 1, wherein the LPFis at least about
 40. 6. The package of claim 1, wherein the LPF is atleast about
 50. 7. The package of claim 1, wherein the LPF is at leastabout
 60. 8. The package of claim 1, wherein the LPF is at least about80.
 9. The package of claim 1, wherein the LPF is at least about 100.10. The package of claim 1, wherein at least one of the monolayercontainer and monolayer closure comprises titanium dioxide.
 11. Thepackage of claim 1, wherein at least one of the monolayer container andmonolayer closure comprises at least one color pigment.
 12. The packageof claim 1, wherein at least one of the monolayer container andmonolayer closure comprises plastic.
 13. The package of claim 1, whereinthe monolayer container and the monolayer closure comprise plastic. 14.The package of claim 1, wherein the package contains dairy product. 15.The package of claim 1, wherein the package contains liquid dairyproduct.
 16. The package of claim 15, wherein the liquid dairy productcomprises milk.
 17. Light protection monolayer closure comprising a topportion having a thickness of at least about 50 mil.
 18. The closure ofclaim 17, wherein the top portion thickness is from about 50 mil toabout 70 mil.
 19. The closure of claim 18, wherein the top portionthickness is from about 50 mil to about 60 mil.
 20. The closure of claim17, wherein the closure top portion has an LPF of at least about
 50. 21.The closure of claim 17, wherein the closure is white.
 22. The closureof claim 17, wherein the closure comprises TiO₂.
 23. The closure ofclaim 22, wherein the closure further comprises one or more pigments.24. The closure of claim 23, wherein the one or more pigment is yellowpigment.
 25. The closure of claim 23, wherein the one or more pigment isblack pigment.
 26. The closure of claim 17, wherein the closurecomprises plastic.
 27. The closure of claim 26, wherein the closurecomprises at least one material selected from the group consisting ofHDPE, LLPE, PET, and PS.